TRegressFun Type

Summary

Defines regression function.

Declaration

TRegressFun = function(B: TVec; X: TSample): TSample;

Description

The type describes the regression function of several regression parameters (B array) and independent variable X. The TRealFunction is used in several regression procedure.

See Also
TDeriveProc

Example 1

Some examples of regression function:

Polynomial of 2nd degree (parabola)

    // y=b0*x*x + b1*x + b2
    function SimpleParabola(B: TVec; X: TSample): TSample;
    begin
      Result := b[0]*Sqr(x) + b[1]*x + b[2];
    end;

    double __fastcall SimpleParabola(TVec * b, double x)
    {
      double* B = b->PValues(0);
      return B[0]*x*x + B[1]*x + B[2];
    }

    private double SimpleParabola(TVec B, double x)
    {
      return B[0]*x*x + B[1]*x + B[2];
    }

Example 2

"Eckerle4" function from NIST files:

    function Eckerle4(B: TVec; X: TSample): TSample;
    begin
      Result := B[0]/B[1] * Exp(-0.5*Sqr((X-B[2])/B[1]));
    end;

    double __fastcall Eckerle4(TVec* b, double x)
    {
      double* B = b->PValues(0);
      
      double sqrterm = (x-B[2])/B[1])*(x-B[2])/B[1]);
      return B[0]/B[1] * Exp(-0.5*(sqrterm));
    }